JPH1123484A - Pattern inspection method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the reduction of excess detection of defects by obtaining the patterns of a hole and a land as the first and second pattern and determining the quality of the land on the basis of a part inside the enlarged first pattern that the first pattern is enlarged and a part outside the second pattern. SOLUTION: A PGA(pin grid array) package 10 is step-driven by a transferring device 18, and the image of the surface of the package 10 is formed on an image pickup device 23 by an image-forming lens 22 to output a video signal VS. The signal VS is compared with slice levels SL1 and SL2 at binarizing circuits 24 and 25, and the binarized output is stored in image memories 26 and 27. An image processing circuit 28 enlarges the pattern of a pin inserting hole in the transmitted binarized image to obtain the transmitted binarized enlarged image of the enlarged pattern of a pin inserting hole on the one hand and obtains a reflected binarized reversed image by reversing the logical value of each pixel of the reflected binarized image to obtain an AND image on the other hand. A determining circuit 29 determines whether a pin land is normal or defective on the basis of the AND image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and apparatus for inspecting a ring-shaped land around a hole formed in a pin grid array (PGA) package or the like.

[0002]

2. Description of the Related Art FIG. 7 shows a PGA package 10 to be inspected. A bonding pad 12 is formed around a semiconductor chip 11 mounted in a central concave portion of the package. The bonding pad 12 and a pad (not shown) on the semiconductor chip 11 are connected by a bonding wire 13. I have. PGA Package 1
Pin insertion holes 14 are formed in a lattice shape in the outer peripheral portion of the surface 0, and a ring-shaped pin land 15 is formed around each of the pin insertion holes 14 around the pin insertion holes 14. Pinland 15
Are connected to the bonding pads 12 inside the PGA package 10. A pin is inserted into the pin insertion hole 14, and this pin is soldered to the pin land 15.

The appearance inspection of the PGA package 10 is performed before inserting the pins into the pin insertion holes 14. FIG. 8 is an enlarged partial cross-sectional view of FIG. Pin insertion holes 141 to 143
The inner peripheral surface and both end edges thereof are plated, and both end edges are pin lands, and pin lands 151 to 153 are formed.
Is on one side. Pin lands 151-153
Is formed, a resin film 16 is applied as a protective film on the surface of the PGA package 10, and the pin lands 151 to 153 are removed by etching.
If the removal is incomplete and the residual resins 162 and 163 exist on the pin lands 152 and 153, respectively, the soldering between the pins and the pin lands 152 and 153 will be poor depending on the degree.

[0004]

Even if the outer periphery of the pin land is covered with the resin film, the soldering can be performed normally if there is no residual resin near the pin insertion hole of the pin land. Also, the diameter of the pin insertion hole is about 0.6 mm, but there is a variation in the diameter, so that the soldering can be performed normally if there is no residual resin. However, it differs depending on the diameter of the pin insertion hole.

[0005] If the PGA package 1 is determined to be defective merely by the presence of residual resin on the pin lands, despite the fact that soldering can be performed normally,
Since the yield of “0” is deteriorated, it is necessary to minimize the detection of excessive defects. SUMMARY OF THE INVENTION An object of the present invention is to provide a pattern inspection method and apparatus capable of reducing excessive detection of defects in view of such a problem.

[0006]

According to a first aspect of the present invention, there is provided a pattern inspection method for inspecting a pattern of a ring-shaped land formed around a hole of a base material, wherein the pattern of the hole is formed by a first pattern. , The land pattern is acquired as a second pattern, the first pattern is enlarged to acquire an enlarged first pattern, and the enlarged first pattern is acquired based on a portion inside the enlarged first pattern and outside the second pattern. The quality of the land is determined.

[0007] The first and second patterns may be either positive or negative. According to this pattern inspection method, since the enlarged first pattern is obtained by enlarging the first pattern, the quality of the land is accurately determined in consideration of the variation in the size of the hole, and the quality of the enlarged first pattern is increased. This has the effect of reducing overdetection of defects as compared with the case where a fixed pattern is used instead, and greatly contributes to the improvement of inspection quality.

According to a second aspect of the present invention, in the first aspect, the hole is a through hole, and the surface of the base opposite to the land is illuminated with light whose traveling direction includes the direction of the through hole. At the same time, the land is illuminated and the land is imaged.
The first pattern is obtained by binarizing, and the second pattern is obtained by binarizing the image of the land at the second slice level by the logic opposite to the binarization.

According to this pattern inspection method, the first pattern and the second pattern are obtained at the same time, so that the processing can be performed at a higher speed than when these patterns are separately obtained. This eliminates the effect of improving image processing accuracy. According to a third aspect of the present invention, in the first or second aspect, before the first pattern is enlarged, the first pattern is reduced and then enlarged to remove a noise pattern.

According to this pattern inspection method, by enlarging after pattern reduction, a minute noise pattern is removed at the time of reduction and expansion of the noise pattern is prevented, so that the quality of the land can be more accurately determined. This has the effect that it becomes possible. In the pattern inspection method according to the fourth aspect, in any one of the first to third aspects, if there is a pixel in the enlarged first pattern and outside the second pattern, it is determined as a land defect.

According to this pattern inspection method, there is an effect that the configuration is simplified. In a pattern inspection method according to a fifth aspect, in any one of the first to third aspects, a land defect is determined if the size of a portion inside the enlarged first pattern and outside the second pattern is equal to or larger than a set value. . According to this pattern inspection method, there is an effect that excess defect detection can be reduced as compared with the case of the fourth aspect.

According to a sixth aspect of the present invention, in a pattern inspection apparatus for inspecting a pattern of a ring-shaped land formed around a hole of a base material, the pattern of the hole is obtained as a first pattern, and the pattern of the land is obtained as a first pattern. A pattern acquisition device that acquires two patterns, an image processing circuit that enlarges the first pattern to acquire an enlarged first pattern, and obtains a portion inside the enlarged first pattern and outside the second pattern; 1
A judgment circuit for judging pass / fail of the land based on a portion inside the pattern and outside the second pattern.

According to a seventh aspect of the present invention, in the pattern inspection apparatus according to the sixth aspect, the hole is a through-hole, and the pattern acquisition device is arranged such that the traveling direction is opposite to the land of the base material by light including the direction of the hole. A lighting device for illuminating the land and illuminating the land, an imaging device for imaging the land and outputting a video signal, and a first binarizing circuit for binarizing the video signal at a first slice level And a second binarizing circuit for binarizing the video signal at a second slice level, and the output of the first binarizing circuit are written, and the hole pattern is created as a first pattern. And an image memory in which the output of the second binarization circuit is written and the land pattern is created as a second pattern.

In the pattern inspection apparatus of the present invention, the image processing circuit may reduce the noise pattern by enlarging the first pattern before enlarging the first pattern before enlarging the noise pattern. Remove. Claim 9
The pattern inspection apparatus according to any one of claims 6 to 8,
In one embodiment, the determination circuit determines that there is a land defect when there is a pixel in the enlarged first pattern and outside the second pattern.

According to a tenth aspect of the present invention, in the pattern inspection apparatus according to any one of the sixth to eighth aspects, the determination circuit includes:
If the size of the portion inside the enlarged first pattern and outside the second pattern is equal to or larger than a set value, it is determined that the portion is a land defect.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 shows a schematic configuration of a pattern inspection apparatus according to a first embodiment of the present invention. PGA Package 10
Are mounted on the transport device 18 and are step-driven, and are inspected one by one in the inspection unit. In this inspection department,
A planar lighting device 20 is arranged below the PGA package 10, and a ring-shaped lighting device 21 is arranged above the PGA package 10. The surface of the PGA package 10 is imaged on the image sensor 23 by the image forming lens 22, and the image sensor 23 outputs a video signal VS. An imaging device is configured by the imaging element 23 and the imaging lens 22.
The image sensor 23 is a point sensor, a line sensor, or an area sensor. In the case of a point sensor or a line sensor, a scanning optical system (not shown) is used and the PGA package 10 is continuously moved by the transport device 18 or a stage (not shown). To obtain a video signal VS of a two-dimensional image.

FIG. 2A is a plan view of a part of the inspection object, and the hatched part shows the resin film 16. FIG. 2B shows the waveform of the video signal VS along the line AA in FIG. In order to make a processing target image described later more accurate, the video signal VS of the light transmitted through the pin insertion holes 141 and 144 becomes a saturated output (100%), and the video signal VS of the light reflected by the pin lands 151 and 154.
The power of the lighting devices 20 and 21 is adjusted so that is approximately 50% of the saturation output.

In FIG. 1, a video signal VS is supplied to binarization circuits 24 and 25, and a slice level S
It is binarized in comparison with L1 and SL2. In order to make the processing target image more accurate, the slice levels SL1 and SL2 are set to about 75% and about 25% of the saturation output of the video signal VS, respectively, as shown in FIG.

The outputs of the binarization circuits 24 and 25 are written to image memories 26 and 27, respectively. The transmitted binary image 271 and the reflected binary image 272 shown in FIG. 3 are images (processing target images) stored in the image memories 26 and 27, respectively, corresponding to FIG. For example, the pixel value of the hatched portion is “1”, and the pixel values of the other portions are “0”.

The image processing circuit 28 shown in FIG. 1 performs the processing shown in FIG. 3 on these images. That is, on the one hand, the pin insertion pattern 141A in the transmission binary image 271
And 144A are enlarged to form pin insertion hole enlarged patterns 141B and 144B, respectively.
On the other hand, the logical value of each pixel of the reflection binary image 272 is inverted to obtain a reflection binary inverted image 282. Then, the transmission binary enlarged image 281 and the reflection binary inverted image 282
The AND operation is performed on each of the corresponding pixels to obtain an AND image 283. The residual resin pattern 164A is a part of the resin film present inside the pin insertion hole enlarged pattern 144B.

The determination circuit 29 in FIG.
It is determined whether the pin land is normal or defective based on the logical product image 283 obtained in step (1). In the case of FIG. 3, since the pixel of “1” does not exist inside the pin insertion hole enlarged pattern 141B, the pin land 151 of FIG. 2A is determined to be normal, and the pin insertion hole enlarged pattern 144B.
Since there is a pixel “1” inside the pixel, the pin land 154 in FIG. 2A is determined to be defective.

For example, as shown in FIG. 6C, when the pixel of interest is “1”, all the 3 × 3 pixels around the pixel are set to “1” as shown in FIG. . In this case, the transmission binary enlarged image 281
It is created in a storage area different from the value image 271. In the first embodiment, the lighting devices 20 and 21 and the binarizing circuit 2
By setting the two slice levels SL1 and SL2 as shown in FIG. 2B using 4 and 25, the transmission binary image 271 and the reflection binary image 272 of FIG. 3 are obtained at the same time. Therefore, it is possible to perform processing at a higher speed than in the case where these are separately acquired, and the positional deviation between the two images is eliminated, so that the image processing accuracy is improved.

Further, since the image 271 of the pin insertion hole is obtained and enlarged, the variation in the size of the pin insertion hole is taken into consideration, and the determination by the determination circuit 29 determines the fixed pattern instead of the enlarged pattern. More accurate than when used. [Second Embodiment] In the first embodiment, if at least one pixel of “1” is present in the logical product image 283 of FIG. 3, it is determined that the pixel is defective. In this case, the noise included in the video signal VS may cause a defect to be determined even though the residual resin pattern does not exist in the pin insertion hole enlarged pattern. Further, even if a residual resin pattern exists in the pin insertion hole enlarged pattern, soldering can be performed normally if the size is small.

Thus, in the second embodiment, the size of the residual resin pattern 164A is measured by the determination circuit 29 of FIG. 1, and if the size is equal to or larger than the set value, it is determined that the pattern is defective. For this measurement, for example, a known radial length measuring sensor 30 as shown in FIG. 4 can be used.
The radial length measurement sensor 30 obtains the number of “1” pixels continuing from the center to the outside with respect to the pixels radially extending from the center.
If the number of pixels is equal to or greater than 00 μm, it is determined that the pixel is defective. In the case of FIG. 4, the residual resin patterns 164B and 1
It is not determined as a defect by the presence of 64C, but is determined as a defect by the presence of the residual resin pattern 164A.

According to the second embodiment, whether the defect is normal or defective is determined based on the size of the residual resin pattern in the pin insertion hole enlarged pattern. can do. [Third Embodiment] In FIG. 3, when the pattern is enlarged, the noise pattern is also enlarged, and the noise pattern may be erroneously determined as a defect due to the connection with the residual resin pattern. Therefore, in the third embodiment, as shown in FIG.
A noise pattern removal circuit 31 is connected between the value conversion circuit 24 and the image memory 26. Other configurations are the same as those of the first embodiment or the second embodiment.

FIG. 6 shows an example of a noise pattern removing method by the noise pattern removing circuit 31. In this method, a pattern is reduced and then enlarged to remove a minute noise pattern at the time of reduction, and only the unremoved pattern is enlarged to return to the original pattern. That is, for all pixels, for example, if all 3 × 3 pixels centered on the target pixel are all “1”, the pattern is reduced by setting the target pixel to “1”. As a result of this processing, all the pixels of “1” disappear in FIG. 6A, and 3 × 3 pixels are reduced to one pixel at the center in FIG. 6B. next,
As shown in FIG. 6C, the pattern enlargement processing described in the first embodiment is performed.

According to the third embodiment, the image processing circuit 2
8 prevents the noise pattern from expanding, so that the determination by the determination circuit 29 can be performed more accurately. The present invention also includes various modified examples.
For example, by using the inverted output of the binarizing circuit 25, the reflected binary inverted image 282 in FIG.

Using the inverted output of the binarization circuit 24,
A configuration in which the NOR image of the reflection binary image 272 and the inverted image of the transmission binary enlarged image 281 may be obtained without acquiring the reflection binary inverted image 282 in FIG. Binarization circuit 2
Even if both of the inversion outputs 4 and 25 are used, the same pass / fail judgment result can be obtained because the logical operation in the image processing circuit 28 can cope with the inversion output.

Further, the noise pattern removing circuit 3 shown in FIG.
1 may be configured to remove isolated '1' pixels as pattern noise. The inspection target may be a land formed in a through-hole of a multilayer board into which pins are not inserted, as long as a ring-shaped pattern is provided around the hole. The memories 26 and 27 are formed as one memory, and the inside thereof is stored in the storage area of the output of the binarization circuit 24 in software.
The configuration may be divided into a storage area for the output of the value conversion circuit 25.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a pattern inspection apparatus according to a first embodiment of the present invention.

FIG. 2A is a plan view of an inspection target, and FIG. 2B is a diagram illustrating a video signal waveform along an AA line in FIG.

FIG. 3 is an explanatory diagram of image processing by the apparatus of FIG. 1;

FIG. 4 is an explanatory diagram of a normal / defect determination process according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a schematic configuration of a pattern inspection apparatus according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating an example of a noise pattern removing method.

FIG. 7 is a diagram showing a pin grid array package to be inspected.

FIG. 8 is an enlarged partial cross-sectional view of the package of FIG. 7;

[Explanation of symbols]

 10 PGA Package 14, 141-144 Pin Insertion Hole 141A, 144A Pin Insertion Pattern 141B, 144B Pin Insertion Hole Enlargement Pattern 15, 151-154 Pin Land 151A, 154A Pin Land Pattern 16 Resin Film 162-164 Resin Resin 164A-164C Resin Resin Pattern 20, 21 Illumination device 22 Imaging lens 23 Image sensor 24, 25 Binarization circuit 26, 27 Image memory 271 Transmission binary image 272 Reflection binary image 28 Image processing circuit 281 Transmission binary enlarged image 282 Reflection binary inversion Image 283 Logical product image 29 Judgment circuit 30 Radial length measurement sensor 31 Noise pattern removal circuit SL1, SL2 Slice level VS Video signal

Continued on the front page (72) Inventor Susumu Haga 4-1-1, Uedanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Hidetoshi Oba 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (10)

[Claims] 1. A pattern inspection method for inspecting a pattern of a ring-shaped land formed around a hole of a base material, wherein the pattern of the hole is obtained as a first pattern, and the pattern of the land is obtained as a second pattern. Acquiring the enlarged first pattern by acquiring the first pattern, and determining the quality of the land based on a portion inside the enlarged first pattern and outside the second pattern. Inspection methods. 2. The above-mentioned hole is a through hole, and the surface of the substrate opposite to the land is illuminated with light whose traveling direction includes the direction of the through hole, and the land is simultaneously illuminated to image the land. Then, the first pattern is obtained by binarizing the image of the land at the first slice level, and binarizing the image of the land at the second slice level by logic opposite to the binarization. The pattern inspection method according to claim 1, wherein the second pattern is obtained. 3. The pattern inspection method according to claim 1, wherein, before enlarging the first pattern, a noise pattern is removed by reducing and enlarging the first pattern. 4. The pattern inspection method according to claim 1, wherein a land defect is determined when there is a pixel inside the enlarged first pattern and outside the second pattern. 5. The method according to claim 1, wherein a land defect is determined if the size of the portion inside the enlarged first pattern and outside the second pattern is equal to or larger than a set value. The pattern inspection method described. 6. A pattern inspection apparatus for inspecting a pattern of a ring-shaped land formed around a hole of a base material, wherein the pattern of the hole is obtained as a first pattern, and the pattern of the land is obtained as a second pattern. A pattern acquisition device to acquire, an enlarged first pattern obtained by enlarging the first pattern,
An image processing circuit for obtaining a portion inside the enlarged first pattern and outside the second pattern; and a determining circuit for judging pass / fail of the land based on the portion inside the enlarged first pattern and outside the second pattern. A pattern inspection apparatus characterized by having: 7. The illumination device according to claim 7, wherein the hole is a through hole, and the pattern acquisition device illuminates the surface of the substrate opposite to the land with light whose traveling direction includes the direction of the hole to illuminate the land. An image pickup device for picking up an image of the land and outputting a video signal; and a first 2 which binarizes the video signal at a first slice level.
A binarizing circuit, and a second binarizing unit that binarizes the video signal at a second slice level.
The output of the first binarization circuit is written, the hole pattern is created as a first pattern, the output of the second binarization circuit is written, The pattern inspection apparatus according to claim 6, further comprising: an image memory in which a pattern is created as a second pattern. 8. The image processing circuit according to claim 6, wherein the image processing circuit removes a noise pattern by reducing and then expanding the first pattern before expanding the first pattern. Pattern inspection device. 9. The apparatus according to claim 6, wherein the determination circuit determines a land defect when a pixel in the enlarged first pattern and outside the second pattern exists. Pattern inspection equipment. 10. The method according to claim 6, wherein the determination circuit determines that a land defect exists when a size of a portion inside the enlarged first pattern and outside the second pattern is equal to or larger than a set value. The pattern inspection apparatus according to any one of the above.